Transseptal puncture (“TP”) of the interatrial septum is a technique utilized to access the left atrium during surgical procedures. TP is involved in many left heart trans-catheter interventions including left atrial fibrillation ablation, left atrial appendage occlusion, mitral valve valvuloplasty, and mitral valve repair using clips. Although the procedure has been used since 1959, it remains a difficult procedure for physicians to perform, especially for patients with an atypical anatomy or a small fossa ovalis.
Typically, physicians utilize fluoroscopy during a TP procedure and rely on anatomical landmarks with high attenuation (e.g., spine and ribs) to localize the interatrial septum. Catheters in the aortic root, the coronary sinus, and other anatomical structures may provide additional visual guidance. However, because fluoroscopy is a 2D imaging modality without depth information, it is difficult to estimate the 3D location of the interatrial septum without using multiple fluoroscopic views to verify the location.
If physicians cannot accurately locate the interatrial septum during a TP procedure, various complications may occur. A puncture outside the interatrial septum may result in severe complications, such as aortic puncture, cardiac perforation, and systemic embolization. Moreover, a puncture inside the interatrial septum is not guaranteed to be appropriate for a certain intervention.
C-arm computed tomography (CT) has emerged as an effective technique for providing a 3D cardiac model for use during surgical procedures. One of the advantages of C-arm CT over other imaging systems, e.g., conventional CT or magnetic resonance imaging (MRI), is that C, arm CT is able to capture both a 3D patient-specific cardiac model and a 2D fluoroscopic image with the same device. However, the use of C-arm CT imaging data for interatrial septum estimation present some challenges. There may be severe cardiac motion artifacts as well as streak artifacts caused by various catheters inserted in the heart. In addition, in many cardiac treatments, the contrast injection is only inside the left atrium, while the right atrium has no contrast at all. Thus, the interatrial septum wall is often not visible and it is very difficult, if not impossible, to accurately delineate the boundary of the interatrial septum wall.